Offensive missiles such as any number of cruise missiles are constructed to fly at low altitudes, just above treetops or water surfaces, to avoid detection by enemy radar. In such situations a targeted ship, for example, may have just a few seconds to first identify the threat and then take counter-measures such as firing one of its defensive missiles. Normally, a land or ship borne defensive missile is launched from a canister or missile launcher in a generally vertical direction, and it must first achieve sufficient velocity before its airfoil surfaces are able to effect any substantial maneuvers. This generally translates into having the missile reach an altitude of thousands of feet before it is able to pitch over and begin seeking the incoming missile threat. The time needed for these maneuvers is considered much too long.
A number of systems have been developed in an attempt to address this problem. Some of these concepts may be categorized as jet tabs, moveable nozzles, liquid injections and jet vane systems. However, devices using these systems are generally inadequate for many current applications. Retractable jet vanes, for example, are incompatible with the need for folding missile tail control surfaces, a necessary requirement for any launch canister loaded missile with stringent volume constraints.
Detachable jet tab systems including auxiliary propulsion units pivotally attached to the missile fins for coupled bidirectional motion, similarly conflict with folding control surfaces and require increases in the launch canister cross-section for additional volume external to the missile fuselage structure. A systems of this sort is shown in U.S. Pat. No. 4,844,380.
Moveable nozzle systems are heavy and complicated and are not detachable. Liquid injection systems do not provide sufficient thrust vector angles.
Existing jet vane mechanisms are either nondetachable or incorporate actuation systems with feedback control electronics redundant to the missile's steering control unit. Nondetachable jet van mechanisms limit missile range and performance with rocket thrust degradation throughout the missile's trajectory. Self actuation jet vane mechanisms are also heavy and inherently complicated, hence, require more rocket propellant for missile launch and lack sufficient reliability.
A shipboard defense system made by Raytheon and used on the Canadian SEA SPARROW missile system has vanes in the missile exhaust plume. However, this system includes elements that are redundant to those found on the missile, which adds unnecessary weight, is overly complicated and is very costly.
The numerous prior attempts to provide missile control at launch has yet to produce an optimal system.
Hence, there is a need in the art for further improvements in systems and techniques for providing missile control during launch.